Whereas traditional search engines provided results from sources such as static Web pages that changed infrequently, modern search engines use sources such as tweets, blog posts, comments, or online news stories that change frequently, and try to deliver results from those sources soon after they appear on the Web. Such results are often called real-time results.
Browsing real-time results means browsing a result set that changes as it is being browsed. Prior to the present invention, allowing the user to browse real-time results effectively has been an open problem.
Some search engines that specialize in real-time results show results ordered by recency, most recent first, in a fast scrolling display. This is not useful as an information retrieval tool because relevant results are swamped by social chatter. Twitter Search supplements such a fast scrolling display with a set of three results deemed to have high relevance, which change infrequently. This is only marginally more useful as an information retrieval tool, due to the fact that only three high-relevance results are shown.
The search engine Topsy ranks results by a weighted combination of recency and relevance, and groups results in pages like traditional search engines do, with a page menu displayed at the bottom of each page for result set navigation. Ranking results by a weighted combination of recency and relevance is useful, but it is difficult for a user to keep track of what results he or she has seen. For example, a user may miss a result that moves from page 2 to page 1 (due to an increase in relevance that outweighs a decrease in recency) as the user advances from page 1 to page 2 while browsing the result set.
Meredith Morris of Microsoft has proposed highlighting results that are new when the user re-executes a query, identifying new results “by comparing the search results of the re-executed query to the previous query” (US Patent Application 2009/0006358, Paragraph 0058). Such a comparison is practically impossible for most queries issued against the World-Wide Web, whose result sets have millions of elements. Furthermore, the proposal does not address the pagination issue, i.e. the problem of keeping track of what results have been seen when results are grouped into pages and the user navigates from one page to another. Furthermore, the proposal would not solve the problem even if it were combined with result set pagination, as it would still be possible to miss a result that moves from page 2 to page 1 as the user advances from page 1 to page 2. It is to be noted that, for example, the ranking of an important tweet based on a weighted combination of recency and relevance may go up for a few hours as it is retweeted, retweets being a signal used to compute relevance, before going down later as the tweet becomes old and is no longer retweeted.